Because bees have evolved to carry and disseminate pollen and other microscopic matter, it is a natural extension to use bees to carry microscopic biological control agents to protect plants from certain insect and diseases. Over the last few years, several authors have reported using honey bees to carry biological antagonists to control insects and diseases that attack plants. Gross et al. (1994) used honey bees as disseminators of a virus that controlled the corn earworm on crimson clover and developed an applicator for that purpose. Thomson et. al (1992) used commercial pollen trays to inoculated the bees with a biological antagonist that protected apples and pears from fire blight. Peng et al. (1992) designed a dispenser to contaminate honey bees with a biological control agent to control Botrytis fruit rot on strawberries. Each of these applicator/disseminator devices were effective in inoculating the bees with the biologicals but they are cumbersome and difficult to use especially by a non professional bee keeper.
Because recent research has shown that bee disseminated biological antagonists can control two different diseases on apples, pears, and strawberries, there is potentially a large market for this biological approach. Currently in the United States, there are about 45,000 acres of strawberries, 330,000 acres of apples and 67,000 acres of pears under cultivation. Each year these crops have to be pollinated and protected from Botrytis fruit rot or fire blight.
A number of known devices are mounted on the opening of bee hives which direct bees in and out of the hive. Such devices frequently surface-contaminate a bee with live pollen for dissemination outside the hive. Most of these devices include a hive entrance modifier forming a downwardly sloping ramp used by entering and exiting bees. Pollen is poured into the funnel-shaped region formed by the ramp and it is picked up by the bees as they exit the hive. A disadvantage of these devices is that they need to be serviced frequently (every 1-2 hours) by adding teaspoons of pollen or biocontrol agents into the funnel. If refilling is not done frequently, than bees exiting the hive are without their pollen or biocontrol payload.
U.S. Pat. Nos. 2,435,951 (Antles), 2,485,879 (Harwood), and 3,371,360 (Antles et al.) disclose hive exit devices, as described above, that require frequent refilling and only coat the bees as they exit the hive. Because the entire entrance/exit region of the hive is not totally covered by these devices, some exiting bees avoid the device and do not come in contact with the pollen or biocontrol agent. This obviously reduces biocontrol efficacy in the field. Although U.S. Pat. No. 4,594,744 (Ferrari) discloses a device that forces the bees to contact the pollen or the biocontrol material as they exit the hive, the device requires frequent refilling.
U.S. Pat. No. 3,069,702 (Reed) has a large storage area and contains a feeder wheel that automatically deposits the material onto the bees. However, it has moving parts that can fail and require maintenance. In addition, this feeder constantly deposits material across the exit of the hive even when the bees are inactive. Depending on the formulation of the biocontrol agent, clogging of the apparatus is possible, resulting in less material being applied to the bees.
U.S. Pat. No. 4,412,363 (Robson) discloses an apparatus for collecting and distributing pollen that is dimensioned to fit within the stack of hives (supers) that form a segmented bee colony. The apparatus includes a removable tray, but removing and inserting a new tray can be difficult because of dead bee bodies and caking problems.
U.S. Pat. No. 5,348,511 (Gross et al.) discloses a device placed in front of beehives to disseminate biocontrol agents. Although this device has a removable tray, removing and inserting a new tray can be difficult because of dead bee bodies and caking problems. In addition, a major disadvantage of this device is that it requires cutting a fairly large hole in the hive for attachment.
Most of the currently available devices only hold a few teaspoons of material and need to be recharged frequently. Although this may be fine for research purposes using only a few hives, it does provide practical limitations for commercial applicability.